Cloning Circuit Board Current Loop Design

Cloning Circuit Board Current Loop Design must follow below rules:

Digital current should not flow through analog devices.
When the digital device is switched, the digital current in the loop is quite large, but it is only instantaneous. This phenomenon is caused by the effective inductance and impedance of the ground wire.

For the inductance part of the ground plane or ground trace, the calculation formula is V = Ldi/dt, where V is the generated voltage, L is the inductance of the ground plane or ground trace, di is the current change of the digital device, and dt is duration.

The calculation formula for the influence on the impedance of the ground wire is V= RI, where V is the voltage generated, R is the impedance of the ground plane or ground trace, and I is the current change caused by the digital device.

These voltage changes on the reverse engineered PCB board ground plane or ground traces of the analog device will change the relationship between the signal and the ground in the signal chain (that is, the signal’s ground voltage).